Blended traction fluid containing cyclic compounds

ABSTRACT

1. A HYDROCARBON BASE STOCK, USEFUL AS A LUBRICANT HAVING A KINEMATIC VISCOSITY AT 210*F. IN THE RANGE OF 1.5200.0 C.S. AND COMPRISING A BLEND OF (I) AT LEAST ONE PART BY WEIGHT OF A SYNTHETIC OIL CONTAINING AT LEAST 95% OF C13-C40 NAPHTNENE AND (II) FROM 0.1-20 PARTS BY WEIGHT, BASED ON SAID NAPHTNENE OF AT LEAST ONE MEMBER FROM AT LEAST ONE OF THE FOLLOWING GROUPS (A), (B) AND (C): (A) A SYNTHETIC LIQUID C3-C8 OLEFIN HOMOPOLYMER, COPOLYMER, OR TERPOLYMER; (B) A MEMBER FROM GROUP (A) ABOVE WHICH IS AT LEAST PARTIALLY HYDROGENATED; AND, (C) A SEVERLY HYDROREFINED NAPHTNENIC MINERAL OIL LUBE OR PARAFFINIC MINERAL OIL LUBE CONTAINING LESS THAN 1% OF GEL AROMATIC HYDROCARBONS, AND WHEREIN SAID BASE STOCK CONTAINING SAID BLEND HAS A COEFFICIENT OF TRACTION, MEASURED AT 600 FT./MIN., 200*F., 400,000 P.S.I., AT LEAST AS HIGH AS THAT OF ASTM OIL NO. 3.   D R A W I N G

Oct. 22, 1974 3,843531 BLENDED 'nucnon FLUID couumma CYYCLIOCO'IPOUNDS l. N. DULING ETAL Filed June 23, 1971 N wmDoE wMDOI INVENTORS lRL N. DUL'NG DAVlD S. GATES ATTORNEY Patented Oct. 22, 1974 (b) a member of group (a) above which is at least par- 3,843,537 tially hydrogenated, or BLENDED TRACTION FLUID CONTAINING (c) a hydrorefined naphthenic lube or parafiinic lube.

II N. Duling, Gates swarflb In a preferred embodiment, the saturated or partially satmore, Pa" assignors to Sun oil Company ofPennsyL 5 urated hydrocarbon has at least one fused carbocyclrc Vania, Philadelphia, ring or contains at least two carbocyclic rings which are (jonfi uafl im art f li ti 5 N 679, 33, not fused. Preferably the tractant has a kinematic viscosity Nov. 1, 1967. This application June 23, 1971, (KV) at 210 F. in the range of 2-12 and has a coefii- Ser. No. 155,986 cient of traction at least about as high as that of ASTM (310111 1/18, 3/ 10 10 Oil No. 3 at 400,000 p.s.i., 200 F. and 600 ft./min. (the 25259 12 Chums coefficient being measured at 600 ft./min. or at a higher and a lower velocity and extrapolated to 600 ft./min.).

ABSTRACT OF THE DISCLOSURE A preferred blend comprises a blend of C C. naphthene having a glass transition temperature in the range of -90 A method for improving the coeflicient of traction be- 15 to -30 C. and a substantially fully hydrogenated polytween relatively rotatable members in torque transmitting olefin oil.

relationship comprises introducing to the tractive surfaces of said members a lubricant containing from 95-50 weight CROSS REFERENCES o RELATED percent of a hydrocarbon base stock containing a blend of APPLICATIONS a saturated or partially saturated cyclic hydrocarbon con- This application is a continuatiomimpart of our taining from about 12 to 70 carbon atoms (preferably 13 pending application 679,833 (filed Nov. 1 1967) to 40) and at least one member selected from now 595 79 (issued July 27 1971 I p The present application is copending with the following a Synthetlc hquld p y p y related applications, all of which are assigned to the Sun p y of a 3- 8 Olefin; Oil Company (as is the present application).

Serial No. Filing date Title/Inventor(s) 440,614 (now U.S. 3,641,167, issued 2-8-72) 3-17-65 Highly Fluorinated Alkyladamantanes, Robert E. Moore and Edward J. Janoski 621,443 (now abandoned) 3-8-67 Synthetic Lubricants From Low Molecular Weight Olefins, Richard S. Stearns,

Ir N. Duling and David S. Gates. 679,801 (now U.S. 3,597,358, issued 8-3-71) 11-1-67 Traction Drive Transmission Containing Adamantane Compounds as Lubricant,

Irl N. Duling, Frederick P. Glazier, David S. Gates and Robert E. Moore. 679,833 (now U.S. 3,595,796, issued 7-27-71) 11-1-67 Traction Drive Transmission Containing Naphthenes, Branched Parafiins, or glenddssoi (lglatphthenes and Branched Paraflins as Lubricant, Irl N. Duling and avr a es. 679,834 (now U.S. 3,595,797, issued 7-27-71) 11-1-67 Blending Branched Paraffin Fluids for Use in Traction Drive Transmission,

Irl N. Duling, David S. Gates and Marcus W. Haseltine, Jr. 679,851 (now U.S. 3,598,740, issued 8-10-71) 11-1-67 Traction Drive Transmission Containing Paraflinic Oil as Lubricant, Irl N. Duling,

David S. Gates and Thomas D. Newingham. 784,487 (now U.S. 3,646,224, issued 2-29-72) 12-17-68 Conversion of Adamantane Hydrocarbons to Monools, Robert E. Moore. 794,844 (now U.S. 3,608,385, issued 9-28-71) 1-24-60" Friction Drive Fluid, Irl N. Duling and Frederick P. Glazier. 812,516 (now U.S. 3,619,414, issued 11-9-71) 2-19-69 Catalytic Hydrofinishing of Petroleum Distillates in the LubricatingOil Boiling Range, Ivor W. Mills, Merritt 0. Kirk, Jr. and Albert T. Olenzak. 823,138 (now U.S. 3,560,578, issued 2-2-71) 5-8-69 Reaction for Linking Nuclei of Adamantane Hydrocarbons, Abraham Schneider. 850,717 (now abandoned) 8-18-69 Hdrori1efined Lube Oil and Process of Manufacture, Ivor W. Mills and Glenn R. ime er. 876,993 (now U.S. 3,645,902, issued 2-29-72) 11-14-69 Friction or Tractive Drive Fluid Comprising Adamantanes, Irl N. Duling, David S.

Gates, Frederick P. Glazier and Robert E. Moore.

877,462 (now abandoned) 11-17-69 Combination of Traction Drive and Traction Fluid Comprising Saturated Cyclic Compounds, Irl N. Duling and Frederick P. Glazier.

003,256 (now U.S. 3,648,531, issued 3-14-72) 8-19-69 Friction or Tractive Drive Fluid, Irl N. Duling, Frederick P. Glazier, David S.

Gates and Robert E. Moore.

028,942 1-15-70 Prlojcess {in Producing Polyisobutylene Oil, Alfred E. Hirschler and Gary L:

risco 033,023 (now abandoned) 1-29-70 Combination of Tractive Drive and Traction Fluid Comprising Cyclic or Acyclio Compounds, Irl N. Duling and Frederick P. Glazier.

052,300 (now U.S. 3,775,503, issued 11-27-73) 7-6-70 Branched Hydrocarbons in the Cit-C4 Range Having Maximally Crowded Geminal Methyl Groups, Gary L. Driscoll, Irl N. Duling, David S. Gates and Robert W. Warren.

052,301 (now U.S.3,778,487, issued 12-11-73) 7-6-70 Polyisobutylene Oil Having a High Viscosity Index, Gary L. Driscoll, Irl N.

Duling and David S. G ates. 052,771 (abandoned 8-17-71) 7-6-70 Polymerization of Dialkyl Vinylidene Compounds to Oils, Gary L. Driscoll. 052,772 (now U.S. 3,655,808, issued 1-11-72)-.. 7-6-70 Preparation of Oils from Isobutene, Gary L. Driscoll. 052,773 (now U.S. 3,657,369, issued 4-18-72) 7-6-70 Oligimerization oi Isobutene and a-Methylstyrene, Gary L. Driscoll and David L.

err. 053,268 (abandoned 7-23-71) 7-6-70 Phosphorous Compounds Promoted Oligimerization oi Isobutene, Gary L. Driscoll. 056,680 7-20-70 Reaction of Alkyladamantane Compounds to Form Products Having Two Linked Nuclei, Robert E. Moore and Abraham Schneider. 078,190 (now U.S. 3,737,477, issued 6-5-73) 10-5-70 Process of Preparing Synthetic Lubricants From Low Molecular Olefins, Richard S.

Stearns, Irl N. Duling and David S. Gates. 078,191 (now U.S. 3,676,521, issued 7-11-72) 10-5-70 Synthetic Lubricants From Low Molecular Weight Olefins, Richard S. Stearns,

Irl N. Duling and David S. Gates. 080,779 10-14-70 Reaction of Normal Paraffins With Adamantane Compounds, Robert E. Moore. 091,183 11-19-70 Rislictron of Naphthene Hydrocarbons With Adamantane Compounds, Robert E.

oore. 116,841 2-19-71 Lubrication of Controlled-Slip Differential, David S. Gates, Paul E. Hagstrom and Marcus W. Haseltine, Jr. 116,985 2-19-71 Lubricant for Controlled-Slip Differential, Thomas D. Newingham, Alexander D.

Recchuite, John Q. Griffith, III and Marcus W. Haseltine, Jr. 133,637 4-13-71 Combination of Tractive Drive and Traction Fluid Comprising Saturated Cyclic Compounds, Irl N. Dulin and Frederick P. Glazier. 134,095 (abandoned 5-7-72) 4-14-71 Polymerization of Dialkyl inylidene Compounds to Oils, Gary L. Driscoll. 135,295 1-19-71 Cilliemrfi l Reiiction Products of Polyisobutylene, Gary L. Driscoll and Marcus W.

ase rne, r. 137,556 1-26-71 Chemical Reaction Product of Sulfur, Lard Oil and Polyisobutylene, Alexander D.

Recchuite and Gary L. Driscoll. 144,165 (now U.S. 3,715,313, issued 2-6-73) 5-17-71 Traction Transmission Containing Lubricants Comprising Gem-Structured Polar Compound, Marcus W. Haseltine, Jr. and Gary L. Driscoll. 152,303.. 6-11-71 Lubricant Comprising Gem-Structured Organo Compound, Gary L. Driscoll and Marcus W. Haseltrne, Jr.

The disclosure of all of the above-cited applications is hereby incorporated herein by this reference. In particular, these applications disclose blended lubricants which are useful in the present invention, additives which can be useful in such lubricants and processes for making individual components of such blends.

BACKGROUND OF THE INVENTION This invention relates generally to the use of certain naphthenes, partially saturated precursers of naphthenes, hydrorefined mineral oils, polyolefins and branched paraffins as traction fluids. The invention also relates to certain novel traction fluids having good low temperature properties comprising a mixture of at least one branched paraflin having a high viscosity index with at least one naphthene having a low viscosity index and a high traction coeflicient. Preferably the blend of the paralfin and the naphthene has an average molecular weight in the range of 170-1000, more preferably 220-375. More preferably, the paraffin has a high degree of gem branching and a glass transition temperature in the range of 120 to -50 C. and the naphthene has a glass transition temperature (Tg) in the range of 90 to 30 C. The blended fluids of the present invention can contain any of the high traction naphthenic or partially saturated cyclic compounds described in U.S. Pat. Nos. 3,411,369 and 3,440,894. The blended fluids of the present invention can, in general, be superior in fluid and/ or other lubricant properties (such as viscosity index) to the high traction components described in these two patents; furthermore, the process of such blending can allow for more flexibility in choice of tractants for a given application. For example, a high traction component which has poor or unacceptable viscosity properties can be incorporated in a blend, as with a polyisobutylene oil, to produce a useable fluid having good traction and good fluid properties.

The glass transition temperature is further described, for example, by Stearns, Duling and Johnson at pages 306-313, Ind. and Eng. Chem, Volume 5, December 1966 in the paper Relationship of the Glass Transition Temperature to the Viscosity-Temperature Characteristics of Lubricants."

The invention will be described more particularly in connection with the combination of a power transmission system comprising a traction drive and as a lubricant therefor, a composition comprising a hydrocarbon base stock boiling mainly in the lube oil range and having a kinematic viscosity at 210 F. in the range of l.5-200.0 cs., said base stock comprising at least one hydrocarbon corresponding to a perhydrogenated polymer, copolymer or terpolymer of styrene, u-methyl styrene, p-methyl styrene and alkyl, cyclohexyl and alkyl-cyclohexyl derivatives of said perhydrogenated polymer, copolymers, or terpolymers.

Fluorine-substituted derivatives of any of the above hydrocarbons, wherein an average of from one to all of the hydrogen of the hydrocarbon is replaced by fluorine are also useful as traction fluids or components thereof, but are too expensive for most applications.

It is to be understood, however, that in addition to the naphthenes and the branched parafiins described hereinafter (or fluorine-substituted derivatives thereof), such a lubricant can also contain other oils and additives (e.g., from to 50 weight percent) such as an antifoam, a phosphotos-containing friction improver, a viscosity index improver (as a high molecular weight polyisobutylene), a pour point depressant (as a fluorine-containing, saturated polymeric olefin), a corrosion inhibitor (e.g., the alkylene glycol-pentaborate salt types), an anti-oxidant and a sludge dispersant. An especially useful additive, combining detergency, corrosion inhibition and friction improvement at high speeds, is a Mg, Ca or Ba salt (especially a superbased salt) of a weak acid or a partial ester of a weak acid, as thiophosphoric acids, phenols, diesters of phosphoric acid, sulfonated alkyl aromatic hydrocarbons and the like (e.g., super-based barium salts of dithiophosphoric, acid calcium alkyl phenates, and calcium salts of mahogany acids). In general, suitable additives are those having a Friction Ratio at 600 ft./min. (or higher) greater than 0.8 (preferably greater than 0.9). See Rounds, F. G. J. C. & E Data, 5, #4, 499-507 (1960), and the polar compounds described in the aforementioned applications of Driscoll and Haseltine, J r. When the lubricant is applied in mist or aerosol form, the lubricant can contain, to improve reclassification or reduce stray fog, an effective amount (e.g., 0.01-2 weight percent of polymer) of a polymeric additive selected from one or a mixture of acyclic, methacrylic, olefin (e.g., isobutylene) and styrene (e.g., alphamethylstyrene) polymers having a viscosity average molecular weight in the range of l0,000-2,000,000 (preferably 100,00 to 500,000). Such additives are described in commonly-owned, copending application Ser. No. 140,398 filed May 5, 1971 of Amaroso-Coppock-Newingham-Williams, entitled Mist Lubricant Containing Polymeric Additive.

The art has long recognized a need for fluid lubricants having high dynamic coeflicients of friction (e.g., greater than those possessed by naphthenic lube oils), and which are noncorrosive and are sufliciently stable to retain these properties under the severe stress to which such fluids are subjected during use.

Such traction fluids are important components of variable speed power transmission systems which utilize a traction drive or a friction clutch. In particular, the fluids of the present invention are useful in a traction transmission such as that of the attached drawings (Labelled FIG. 1 and FIG. 2) and those shown in the following publications and United States patents:

Kraus, C. E., ASMEPaper 65Md30 (For New York, NY. Meeting, May 17-20, 1956).

Hewko, L. 0., AIAA Paper 67-429 (For AIAA 3rd Propulsion Joint Specialist Conference, Wash, D.C. July 17-21, 1967).

Such blended fluids are also useful in a controlled-slip differential (see the previously cited application of David S. Gates, Paul E. Hagstrom and Marcus W. Haseltine, Jr.).

The traction coefficient, or the dynamic coeificient of friction, which is one measure of the tractive capacity of a contact, can be defined as the ratio of the tangential force to the normal load under rolling-spinning motion. The limiting value of the coeflicient of traction is the coeflicient of traction at slip, which is observed when the rolling contact is on the verge of gross slip. In a given torque friction drive, coeflicient of traction can be computed by knowing the normal load on the contact and by simultaneously measuring the input and output torques.

The essential qualifications of a friction gear transmission fluid comprise especially a high traction coeflicient (which an ordinary lubricant does not possess), and an extremely high thermal stability and resistance to oxidation so as to minimize the necessity for fluid replacement. Another property which a torque converter fluid must exhibit is minimum sludging. Usually, those fluids which have been found to possess high traction coefficients in reference to steel on steel and also which have satisfactory stability and resistance to oxidation generally have high pour points and low viscosity indexes (VI) (e.g., 50 to -400 ASTM-VI), therefore, most traction fluids are not suitable for use at low temperatures. There is a special need for traction fluids having a high viscosity index, particularly for an ASTM-VI or VIP- VI greater than 40, and with a traction coeflicient equal to or better than that of ASTM Oil No. 3.

Although there is not known means of predicting from structural or other chemical considerations Whether a given fluid will be satisfactory for use as a lubricant in a traction drive, a fluid can be tested for an indication of its suitability as a traction fluid by utilizing such equipment and procedures as are described by Almen, J. O. in U.'S. Pat. 2,045,555 or by Rounds, F. G. Journal of C&E Data, 5, pp. 499-507 (1960), and ASLE Transactions, 7, 11-23 (1964). Of particular interest is the research traction test machine of Hewko, L. O. et al., in Proceedings of the Symposium on Rolling Contact Phenomena, pp. 157-185 (1962), Elsevier, Amsterdam, Netherlands. The torque measurement by a Roxana 4- ball tester can also be used to compare traction properties of various fluids.

As is noted in the Hewko paper, the fatigue life of a rolling contact element of a friction drive is inversely proportional to the third power of the load whereas the torque capacity is only directly proportional to the load. As a result, increasing the torque capacity through increasing the coeflicient of traction is far more desirable than through increasing the normal load.

A comparatively small difference in traction coefficient can correspond to a large improvement in lubrication. For example, a increase in the'traction coefl'lcient of the lubricant will increase the durability of the transmission by about 50%.

The coeflicient of traction at a given r.p.m., temperature and contact pressure can varyrsomewhat depending upon the type of test equipment. Most of the traction fluids reported in the literature as having acceptable fluidity and traction properties are not specific chemical compounds of known purity and good stability. Therefore, it is difficult to reproduce or correlate the work reported by various investigators. A pressing need in this area is a standard traction fluid which can be used to correlate traction tests done in various types of transmission and test apparatus. ASTM Oil No. 3 can be used as such a standard.

1,3-(5,7 dimethyl)adamantyl dipelagonate (hereinafter sometimes DMAP) can also be useful as a standard traction fluid because it is readily prepared in high purity, has excellent stability, and has traction properties which are comparable to those of better naphthenic lube oils of the prior art (such as ASTM Oil No. 3). In addition, DMAP is more useful than those naphthenic lubes, as a traction fluid or as a component of a traction fluid, for traction drive automatic transmissions, because it has fluid properties (such as VI) which are greatly superior to those of the usual naphthenic lube oils (e.g., ASTM VI 95 v/s11 for ASTM Oil No. 3). The preparation of DMAP is disclosed in US. Pat. 3,398,165, issued Aug. 20, 1968.

In general (except for oils having a viscosity at 210 C. below 2 cs.), if a fluid is to be useful as a lubricant for a given type of traction transmission, that fluid must have a traction coeflicient in that particular transmission which is at least as high as the traction coefiicient which ASTM Oil No. 3 has in the same transmission at the same test conditions. Therefore, one means of comparing traction fluids is to report their traction coefficients in a particular test (or the average traction coefiicient as in FIG. 1) as being X% higher or lower than that of ASTM Oil No. 3.

SUMMARY OF THE INVENTION This invention relates to the use of certain fluids having high traction coeflicients as lubricants for traction drive transmissions, and to the resulting novel power transmission systems comprising a traction drive transmission and, as a lubricant therefore, said high traction coeflicient fluid. The invention also relates to certain novel hydrocarbon base stocks which are useful as lubricants for a traction drive transmission, particularly for the planetary, ring and cone or friction clutch drive types. The base stocks are also useful for lubricants for friction gears, such as a limited slip differential. The

base stocks are also useful in lubricants for a Wankel engine (this utility being the invention of Richard J. Stenger and Paul E. Hagstrom, and will be the subject of a later filed patent application).

It has been found that fluid G -C naphthenes containing a di(cyclohexyl)alkane or a hydrindan as a structural nucleus are'especially useful as lubricants for friction (traction) drive transmissions, whether the drive is of fixed or variable ratio.

It was further found that an especially useful power transmission system comprises a fixed ratio, roller traction drive of the type described in the aforementioned AIAA paper of Hewko, or a variable ratio drive of the type shown in the attached drawing and labelled FIGS. 1 and 2, and as a lubricant therefor, a composition comprising a hydrocarbon base stock boiling in the lubricating oil range and having an ultraviolet absorbence at 260 millimicrons (260 UVA) below 0.5, said base stock containing, preferably, at least 10% by weight of a C C27 hydrindan. For example, a transmission system comprising the fixed ratio roller traction drive of the Hewko AIAA paper and, as a lubricant, a hydrocarbon base stock containing volume percent of l-cyclohexyl 1,3, 3-trimethyl hydrindan (hereinafter, sometimes CHTMH), 5 volume percent of 2,4-(dicyclohexyl)-2-methylpentane (hereinafter, sometimes DCHMP), and volume percent of a 5 cs. (at 210 F.) polyisobutylene oil wherein over 33% of the repeating units are of the gem-dimethyl configuration, permits the-resulting power transmission system to operate at double the torque throughout of the better of the prior art fluids (naphthenic mineral oils) shown in the Hewko paper.

Additionally, it has been found that fluid C C naphthenes containing a spirodecane, spiropentane, perhydrofluorene, perhydrobiphenyl, perhydroterphenyl, decalin, norbornane, perhydroindacene, perhydrohomotetraphthene, perhydroacenaphthene, perhydrophenanthrene, perhydrocrysene, perhydroindane-l-spirocyclohexane, perhydrocarylophyllene, pinane, camphane, perhydrophenylnaphthalene, adamantane or perhydropyrene, as a structural nucleus, are useful as lubricants for traction drive transmissions. Partially saturated precursors of such naphthenes (such as those described in the applications of Haseltine, Jr. and Driscoll filed May 17, 1971 and June 11, 1971) can also be useful as such lubricants, particularly in the blended base stock. One such precursor is 3-cyclohexyl-1,1,3-trimethylindan.

In one novel and veryuseful embodiment, as is disclosed further hereinafter, certain adamantane hydrocarbons, and fluoro, carboxylic acid, keto, ether or ester de rivatives of such adamantanes, are useful as traction fluids or components of traction fluids. In general, good traction properties appear to be a characteristic of compounds containing the adamantane nucleus or of those naphthenes or alkyl or cycloalkyl naphthenes which are capable of being converted to adamantanes by the Schneider reactions of US. Pat. 3,128,316 or the reactions of US. Pats. 3,275,- 700, 3,336,405 and 3,336,406. However, for better combination of traction properties, fluidity at 210 F. and low temperature properties, those naphthenes containing the hydrindane, decalin, perhydrophenanthrene, cyclohexyl, perhydroterphenyl, perhydroacenaphthene, adamantane or perhydrophenalene nucleus are a preferred group of perhydroaromatics. Fluorinated derivatives of these perhydroaromatics wherein an average of from 1 to all of the hydrogen of the hydrocarbon is replaced by fluorine are also useful as traction fluids or as components of traction fluids. Such fluoro-derivatives are also useful as refrigerants or as a fluid in a Rankin cycle engine. The fluoroderivatives can be prepared by the processes in Ser. No. 440,614.

Generally, those naphthenes having the lower viscosity index (particularly below an ASTM-VI of 0except where the structural nucleus is phenanthrene or adamantane) will have the higher traction coeflicients. These naphthenes can be so used per se, or they can be compounded with additives, such as a dispersant or an antioxidant, or with certain hereinafter described paraffin hydrocarbons or hydrogenated lube oils in order to alter the fluid properties of the resulting lubricant (which, depending upon the desired end use, can be as fluid at room temperature as a gas oil or as stiff as a bearing grease).

A preferred embodiment is a power transmission system comprising a traction drive transmission and as a lubricant therefor, a composition comprising a hydrocarbon base stock boiling mainly above 500 F. and having a kinematic viscosity at 210 F. in the range of 15-2000 (preferably l.8-20) cs., said base stock comprising a perhydrogenated trimer, dimer or codimer of (1) styrene (2) a-methyl styrene,

(3) ,B-methyl styrene, or (4) a monoor dimethyl ring-substituted derivative of To control fluid loss, it is preferred that the base stock boil no lower than in the gas oil range, more preferably the base stock should boil in the lube oil range. Broadly, the oil should boil mainly above 500 F. and, preferably, mainly above 600 F. and (except in greases) have a 90% point below 950 F. Distillation of such stocks is preferably conducted at reduced pressure (as below 5 mm. Hg) including vacuum-steam distillation, to avoid thermal decomposition. Traction greases can be compounded from such base stocks using conventional additives (e.g., soaps).

However, the soap thickeners (e.g., lithium stearate, sodium palmitate, etc.) used in conventional mineral oil greases are fairly good lubricants. The soap can cause, at least to some degree, a reduction in the high friction built into the traction fluid. Therefore, the preferred traction greases are made from non-soap thickeners. Examples of non-soap thickeners are colloidal silica (e.g., Cab-o-sil), a treated clay (e.g., Baragel); clay (e.g., Montrnorillanite with surface activation performed in situ); very fine asbestos and colloidal graphite.

The following Roxana Four Ball Test results show the improvement in traction which is obtained by greases prepared according to this invention, which is the invention of Richard J. Stenger, C. Robert Knott and Arthur T Polishuk and will be the subject of a later-filed application:

The Traction base oil comprised a blend of hydrogenated dimers and trimers, both primarily indan form, of tat-methyl styrene and had a KV of 11.18, KV of 334.9, and ASTM-VI less than 0. Similar greases can be obtained using the blended base stocks of the present invention and non-soap thickeners.

A grease exhibiting such high traction has application wherever a fluid of high traction would be used but where other considerations make impractical the use of a fluid lubricant. An example is lubrication of the linear actuator, Rollguide, made by the Dumore Company of Racine, Wisconsin. Another example is lubrication of the high speed traction drives used with turbine dental drills; Miniature Precision Bearings of Keene, New Hampshire makes such a traction drive. Another example is in the lubrication of roller clutches, where reduced slip increases service life.

A traction fluid or such a grease prepared from a traction fluid, can be used as a lubricant in a cam, roller drive, clutch or any mechanism where the load is concentrated on a series of joints. With such a traction lubricant, service life of the device is increased by decreasing stresses.

Normally, the monomer-free perhydrogenated reaction products will contain components boiling mainly in the range of 250 C. at 0.5 mm. Hg. and the portion chosen for a particular base stock will be obtained by vacuum distillation to recover a fraction of the desired viscosity and flash point. Preferably, the flash point is above F. and more preferably, above 250 F. The viscosity and/or viscosity index of our oils can also be adjusted by dumbbell blending, that is, adding con trolled amounts of light (lower boiling) ends and heavy (higher boiling) ends. However, as will be further disclosed hereinafter, in the case of fluids containing polyolefin oils it is preferred that dumbbell blending be avoided, since it has been found that the better combination of traction coefficient and viscosity index is frequently obtained by choosing a narrow boiling fraction of the desired viscosity, or by blending oils having similar, narrow boiling ranges.

Especially useful components of oils of higher viscosity are the naphthenes corresponding to perhydrogenated trimeric or tetrameric products which are normally present in minor amounts in our perhydrogenated styrene dimerizate but which can be concentrated in the distillation bottoms or in fraction boiling mainly above about 615 F. These trimers and tetramers can also be prepared in high yield by further polymerization of the dimerizate prior to perhydrogenation, especially when the dimerizate is polymerized with additional monomer.

The perhydrogenated dimer or codimer can preferably consist mainly of a C 43 cyclohexyl hydrindan or mainly of a C C di(cyclohexyl)-alkane and usually will consist of a mixture of isomers of both such structures. The structural formulae of the above-mentioned naphthenes is shown, for example, in US. 3,597,358, issued Aug. 3, 1971, of Duling and Gates.

Such a hydrocarbon base stock having an initial traction coeflicient greater than that of ASTM Oil No. 3 at 600 ft./min., 200 R, 400,000 p.s.i. and comprising a blend of naphthenes with a polyolefin and/or hydrogenated petroleum or polyolefin oil can also contain (as in addition to the perhydrogenated dimer, trimer, and tetramer) up to 10 weight percent of aromatic compounds, (or naphthene precursers), such as naphthalenes, phenanthrenes, acenaphthenes, indacenes, hydrindacenes, fluorenes, phenyl indanes, phenylhydrindans and phenyl-alkyl cyclohexyl compounds. Occasionally such aromatics can be useful since they aid in dissolving certain additives in the fluid. However, to insure against degradation of the traction coefficient under the severe operation conditions encountered in a friction drive transmission, we prefer that the hydrocarbon base stock contain less than 5% of unsaturates, or more preferred be substantially free from olefinic and aromatic unsaturation as evidenced by an ultraviolet absorbency at 260 millimicrons (260 UVA) of less than 0.5 and an iodine number less than 5.

When the numerical values reported herein for the traction coefficients of various fluids are compared with the values of other researchers, the values should be adjusted by using the values hereinafter cited for ASTM Oil No. 3 or those for DMAP as the standardization point.

When the hydrocarbon base stock of our invention con sists essentially of naphthenes corresponding to perhydrogenated styrene oligomers (e.g., trimers or dimers of alkyl derivatives thereof), the base stock has a low viscosity index, and, therefore, has poor low temperature properties, such as the pour point. It has been found, surprisingly, that novel traction fluids having a traction coefficient at least 10% greater than that of ASTM Oil No. 3 (at 600 feet per min., 200 F., 400,000 p.s.i.) and having as ASTM viscosity index greater than 40, can be prepared by blending certain branched paraffin hydrocarbons with the perhydrogenated styrene dimer or trimer fluids.

It has been found, surprisingly, that a particularly useful power transmission system comprises a friction drive transmission and, as a lubricant therefore, a hydrocarbon base stock having a 260 UVA below 0.5 and comprising at least one substituted C C cyclohexyl hydrindan having the structure wherein R' is methyl or ethyl and can be different or the same, and R' R RC R' R' R R' and R' are hydrogen or methyl and can be different or the same, said hydrindan being present in an amount of at least percent by weight of the base stock and wherein there g is present from 0.l parts by weight, based on said hydrindan, of a branched paraffin corresponding to a fully hydrogenated liquid C C C or C olefin polymer, copolymer, or terpolymer. Preferably said olefin comprises isobutylene, 3-methylbutene-1, 4-methylpentene-1, or 2,3- dimethylbutene-l. More preferably at least 33 percent (most preferably 90l00%) of the repeating units (exclu sive of terminal methyl groups) of said olefin polymer have the repeating structure FE!!! L' H where R" is hydrogen or methyl, and when R" is hydrogen, R" is isopropyl or isobutyl, and when R" is methyl, R" is methyl, ethyl, isopropyl or isobutyl. We also prefer that the average number of branches per molecule be greater than 3 (with the gem configuration considered as two branches).

Preferred polyolefins are those of the aforementioned applications of Driscoll, of Driscoll and Haseltine, Jr. and of Driscoll, Duling and Gates.

For example, the olefin polymer can have an average molecular weight from 170-1000 when at least 33 percent, and more preferably at least 50%, of the repeating units of the polymer (exclusive of end groups) have the repeating structure CH l el Especially advantageous with such a paraffin (which can be obtained by partial or complete hydrogenation, of a polyisobutylene or of a copolymer or terpolymer of isobutylene with other butenes) is a fluid wherein said hydrindan consists of isomers of l-methyl, 3-cyclohexylhindrindan, or l-cyclohexyl, 1,3,3-trimethyl hydrindan, or mixtures thereof. Also advantageous are blends of such a parafin with a dicyclohexyl alkane or a higher dumbbell oligomer of a styrene.

The nuclear magnetic resonance (NMR) spectrum of a more preferred, highly geminally branched parafiin oil will have a greater peak contributed by the crowded methylene group (at about 8581-) than the peak contributed by uncrowded methylene groups (at about 8851-). See Bartz, K. W., and Chamberlain, N. F., Analytical Chem., 36, #11, 2151-8 (1964) or Warren et al., J. Poly. Sci. part A-l, vol. 9, pp. 717-745 (March 1971). Branched paraflin oils having such a high degree of methylene crowding and a lower degree of uncrowded methylene grouping, are not found to any substantial degree in refined naphthenic or paraflinic petroleum oils.

Preferably the novel hydrocarbon base stock, comprising a blend of at least one C -C naphthene and at least one branched paraffin, has a viscosity in the range of 1.8 to 20.0 cs. at 210 F., a VTF-VI greater than 40, and a traction coefficient at least 10% greater than that of ASTM Oil No. 3 at 600 feet per minute, 400,000 p.s.i. and 200 F. Of special value is such a hydrocarbon base stock containing from 550% by weight of isomers of l-cyclohexyl-l,3,3-trimethyl hydrindan (especially, 4,9- Cis, l-cyclohexyl-1,3,3-tri-methyl hydrindan), and from 1-18 parts of an isobutylene polymer or copolymer per part by weight of hydrindan. Especially useful isobutylene polymers are those of Driscoll, Duling and Gates, U.S. Ser. No. 52,301.

Other useful C C alkyl hydrindans are shown in U.S. 3,597,358.

BRIEF DESCRIPTION OF THE DRAWINGS In the attached drawings FIGS. 1 and 2 represent, respectively, a side view in cross-section and a partial front view in cross-section of a power transmission system comprising a torric traction drive transmission and a lubricant therefor, containing one of the blended traction fluid base stocks of the present invention.

FIGS. 3 and 4 of copending application Ser. No. 679,833, filed Nov. 1, 1967, of Duling and Gates, now U.S. 3,597,385, issued Aug. 3, 1971 present points representing experimentally determined traction coefficients and viscosity temperature function-viscosity indexes (VTF-VI) of a number of hydrocarbon fluids. The scattering of these points illustrates the unpredictability, based on chemical composition above, of the suitability of a particular fluid as a lubricant for a traction transmission. The points and the curves contained on the figures illustrate the generality that a fluid having a high coefiicient of traction tends to have poor low temperature properties. The curves of the two figures also aid in illustrating the discovery that certain fluids have a higher coefficient of traction than other fluids of about the same VTF-VI.

The power transmission system illustrated in FIGS. 1 and 2 is suitable as a continuous automatic variable speed power transmission for automotive use. The torric traction transmission of the figures is similar to that described in Hewko et al., Tractive Capacity and Efficiency of Rolling Contacts, Proceedings of the Symposium on Rolling Contact PhenomenaElsevier, Amsterdam, 1962, pp. 159-161. The power transmission system containing a traction fluid of the present invention comprises a torric drive transmission 1, the traction fluid 2, means, such as a drain 3, a pump 4, and a line 5, to remove said fluid from said transmission and circulate it through a heat exchanger 6 (as an automotive-type radiator), in order that the temperature of the fluid 9 entering the transmission be kept (preferably) below 230 F. (more preferably no higher than 200 F.), and means, such as line 7 and spray nozzle 8, for returning the cooled fluid to the interior of the drive unit.

In operation of the drive unit illustrated in FIGS. 1 and 2, spheroidal steel rollers 10 running on toroidal steel braces 12 and 13 mounted on suitable shafting 14 and 20 are the principal power transmitting components. The toroidal drive in FIGS. 1 and 2 consists of two identical sections transmitting torque in parallel. Each section consists of an input race 13, an output race 12, and three rollers, only one of which 10 can be seen in FIG. 1. Rollers of each section are spaced apart and /6 of the input torque is transmitted by each roller. Both input faces 11 are free to rotate on the output shaft 14 whereas both output races 12 are splined to it. Contact load is applied hydraulically by the piston 15 through a hydraulic fluid 16. The double section arrangement makes the thrust force resulting from the contact load self-contained and eliminates having the ground and thrust through a high capacity thrust bearing. In FIG. 1 the surface of the roller which is in contact with the input face is shown as having the same radius of curvature as that of the face. Such configuration presents a most diflicult lubrication problem. Lubrication is greatly facilitated when the radius of curvature of the contact surface of the roller is less than the radius of curvature of the input face (see U.S. 1,867,553).

The cooled traction fluid 9 which acts as a lubricant and coolant for the drive is supplied through one or more spray nozzles 8 which are preferably directed toward the contact area between the steel roller and the race. Circulation of the lubricant throughout the drive unit is accomplished by splash effect. That is, the bottom section of the casing which houses the differential driver gear 19 acts as a sump for fluid which is circulated to the differential ball bearings 18 as the gear rotates.

A change in ratio is accomplished by tilting all rollers about an axis 22 and thus changing the effective radii of the input and output races. Tilting of the rollers can be accomplished by inclining the rollers through some angle about an axis through the race contacts, thus, steering the rollers into the desired ratio position. The ratio between the two sections is kept constant by locking the two synchronizing collars 17 in a position that makes the speeds of both input races identical. The input races are driven through a ball differential 18 by the differential driver gear 19 mounted on the input shaft 20. This arrangement equalizes the torque between the two sections and permits both the input and output shafts to have the same direction of rotation.

It can be seen that an important requirement of a traction fluid for use in such an automotive transmission system is that it not only has good traction properties, but also is a good lubricant for the differential gear and differential ball, and a good lubricant for the rollers and races. Although such a traction fluid could also be used as the hydraulic fluid 16 in the unit, it is preferred that the hydraulic fluid contain an indicator means, such as a distinctive dye, so that leakage of the hydraulic fluid into the main body of the drive unit can be detected by inspection of the main body of traction fluid, such as by a dip-stick arrangement.

To prevent loss of fluid by vaporization and to insure against introduction of contaminants into the fluid, the transmission system should be fully enclosed and well sealed. With the more volatile fluids, the seals and system should be capable of withstanding pressure exerted by the vaporized portion of the fluid at operating temperatures.

FURTHER DESCRIPTION OF THE INVENTION The perhydrogenated aligomers of styrene, a-methyl styrene, B-methyl styrene and monoand dimethyl ringsubstituted derivatives thereof which are useful in the present invention can be obtained by conventional addition polymerization, as by the dimerization of styrene in aqueous sulfuric (see Rosen, M. 1., J. Org. Chem. 18, 1701 (1953)), followed by high pressure hydrogenation (at least 1000 p.s.i.g., preferably in the range of 2000- 10,000 psi. of H as with Raney nickel catalyst at 200 C. and 3000 psi. of hydrogen. They may also be obtained by polymerization of a vinyl cyclohexane or by hydrogenation of the polymerization product of vinyl cyclohexene or of an alkyl substituted vinyl cyclohexene or by the hydrogenation of the product of the copolymerization of a mixture of vinyl cyclohexenes (including alkyl derivatives thereof), such as by the methods shown in U.S. 2,543,092. Also useful is the hydrogenated vinyl cyclohexene dimer of U.S. 2,590,971.

Further description of such perhydrogenated oligomers and processes of their manufacture can be found in U.S. 3,595,796, issued July 27, 1971, the disclosure of which has been incorporated herein by reference.

Our hydrocarbon base stock boiling mainly above 500 F. having a viscosity above 3 cs. at 210 F. and containing at C -C naphthene is useful as a lubricant for a traction drive transmission due to the high traction coefficient and the good stability of such a hydrocarbon base stock when subjected to prolonged use in such a transmission;

however, such a power transmission system can be limited to applications wherein temperatures lower than about 0 F. are not encountered, such as in submarines or in naval vessels, or for industrial transmissions which are kept in buildings where the temperature is maintained above about 0 F., and preferably above about 40 F. Such a lubricant can, of course, be used in a transmission which will be exposed to temperatures below 0 C., if the oil is maintained at a higher temperature (as by a heater) For low temperature use where extremely high fluid pressures are encountered (as in pressure-equalized external submarine transmissions) a fluid of less than 2 cs. at 210 F. and having somewhat lower traction coefiicient can be useful. Examples of such low viscosity fluids are shown in U.S. 3,595,796.

For automatic variable speed traction drive automotive transmissions, where weight, cost and simplicity of assembly assume high importance and where temperatures as low as 40 C. can be encountered, it is preferred that the lubricant used for the automotive transmission have a viscosity of no greater than about 7000 cs. at 20 F. and have a pour point no higher than about 40 F. Therefore, such a fluid must have a high viscosity index (preferably above 40 VTF-VI and more preferably above and have a viscosity at 210 F. in the range of 315 cs.

As the viscosity index of an oil increases, its traction coefiicient generally decreases. This relationship is particularly striking when the traction coefficient and the VTF-VI of hydrogenated poly-1,3(El-methylbutene-l), Oil 31, is compared with hydrogenated poly(1-Octene).

:For an explanation of the viscosity-temperature function (VTF) and the desirability of using the VTF in the determination of the viscosity index of an oil (e.g. the VTF-VI), see Wright, W. A., ASTM Bull. #215, July 1956, p. 84-86 (TP 140-142) and Stearns, R. S., et al., ICEC Product R & D, Vol. 5, December 1966, pp. 306-313.

Paraflin oils possessing a high proportion of repeating units having the structural formula ELL Lil/'2 HJ wherein R", is hydrogen or methyl and when R" is hydrogen, R";, is i-propyl or i-butyl and when R" is methyl, R is methyl, ethyl, isopropyl or isobutyl, have a higher traction coeflicient for a given viscosity index than do the other parafl'in oils.

One embodiment of the present invention is a power transmission system comprising a traction drive transmission, and as a lubricant therefor, a composition comprising a hydrocarbon base stock having a kinematic viscosity at 210 F. in the range of 1.8-20.0 cs., said base stock comprising at least one branched parafiin wherein at least 33% of the repeating units of said branched paraffin have the structure wherein R is hydrogen or methyl and R is isopropyl or isobutyl. Preferably, the average number of branches per molecule is greater than 3 (with the isopropyl or iso butyl R considered as two branches). Such highly branched parafiins are not found to any appreciable extent in refined petroleum oils. Such a power transmission system is particularly advantageous when said branched paraffin has a pour point below 0 C. and an average molecular weight in the range of 188-560. It is preferred that at least of the repeating units, exclusive of terminal groups, of the branched parafiin have said structural configuration. An especially preferred embodiment of our invention comprises a traction drive transmission and a lubricant comprising at least one such branched paraflin where R is hydrogen when R is isobutyl, and

- 3 when R is methyl, R is isopropyl (see U.S. 3,595,796).

Synthetic liquid C -C olefin polymer, copolymer or per-polymer oils which can be hydrogenated to produce a branched paraffin fluid useful as a component for blending with our naphthene hydrocarbons in order to produce an improved hydrocarbon base for lubrication of traction drive transmissions can be obtained in the manner shown in the following patents and publication: U.S. 3,156,736; 2,993,942; 2,360,446; 2,327,705; 3,007,452; 3,090,822; 2,965,691; 2,224,349; 3,100,808; 1,395,620; 2,500,166; Belgian 663,550; 663,549, Industrial and Engineering Chemistry, Vol. 23, No. 6, p. 606-7. Note that U.S. 1,395,620 and 2,500,166 teach that, under some polymerization conditions, butenes can be converted to naphthenes. Regarding Decalins, see U.S. 2,203,102.

Other preferred branched paraflin components and their manner of preparation are shown in U.S. 3,595,796 and Ser. No. 052,301.

Other oils which are useful as traction fluids or as components of traction fluids (particularly as a third component of our perhymerbranched parafiin blends) are obtained by perhydrogenation of the mixtures of ashydrindacenes and indanyl phenyl alkanes which are obtained when indans are contacted with HF and BF in liquid phase at ll10 C. For example, as is shown in U.S. Serial No. 388,693 of Ronald D. Bushick, filed Aug. 10, 1964, indan can be contacted with HF and BE, to produce benzene, as-hydrindacene and l-(2-indanyl)-3- phenylpropane.

Preferably, the lower boiling components (e.g., benzene and unreacted indan) are removed, as by distillation, prior to perhydrogenation. Similarly, a useful component of a blended traction fluid is obtained by perhydrogenation of the reaction mixtures obtained by contacting octahydroanthracene or octahydrophenanthrene in the presence of an acid catalyst, such as HF-BF or a crystalline zeolite catalyst, as in United States Patent 3,396,203 of Ronald D. Bushick, issued Aug. 6, 1968.

Also useful as a third component of the naphthenebranched paraflin fluids is from 550% of a perhydrogenated poly-l-octene oil having a VTF-VI above 80, preferably above 100.

It is sometimes advantageous to insure that the base stock is free from surface active constituents which can reduce the traction coefiicient of the lubricant. One useful method of removing such surface active constituents is that of U.S. 2,897,144, which comprises foaming the oil (or a portion thereof) with a non-reactive gas and separating the resulting foam from the bulk of the oil.

Another embodiment of the invention comprises a traction drive transmission and as a lubricant therefor, a composition comprising a hydrocarbon base stock having a kinematic viscosity at 210 F. in the range of 1.5200.0 cs., said base stock comprising a C C Decalin containing as substituents at least 1 member selected from the group consisting of C -C alkyl, C -C cycloalkyl, and C -C alkylcyclohexyl and alkylcyclopentyl. For example, any of the alkylnaphthalenes of U.S. 2,549,377 or U.S. 2,626,242 (including hydrocarbon base fluids which contain such alkylnaphthalenes) can be converted to an alkyldecalin fluid by severe hydrogenation (at hydrogen pressures greater than 1000 p.s.i., preferably greater than 1500 p.s.i. and more preferably from 3000-10,000 p.s.i.).

The resulting Decalin fluid can contain up to 10% of residual aromatics (by gel) but, preferably, should contain less than 1% of gel aromatics based on the Decalin and have a 260 UVA less than 0.1. Such traction fluids containing Decalins have a better combination of fluid properties and traction properties and have a longer effective life when used in a traction transmission than do the alkylnaphthalene fluids of the aforementioned patents. One such Decalin is tetraisopropyldecalin.

A novel and preferred type of such a hydrocarbon base drive transmission, has a VTF-VI greater than and a traction coeflicient greater than that of DMAP at 600 ft./min., 400,000 p.s.i. at 200 F., and comprises such a Decalin having a glass transition below --30 C. and from 01-20 parts by weight, based on the total naphthene content of said base stock, of at least 1 fully hydrogenated, synthetic liquid C -C olefin polymer, copolymer, or terpolymer.

An especially useful hydrocarbon base for a traction fluid can be obtained by severe hydrogenation of a refinery stream containing a high percentage of alkylnaphthalenes. Examples of such an alkylnaphthalene-containing refinery stream (and means of concentrating selected fractions) are shown in U.S. 3,595,796.

Both the traction properties and fluid properties of the conventional petroleum oils which normally contain from 15-60% gel aromatics or of the usual hydrotreated and/or acid treated and/or solvent treated naphthenic oils (which can contain as little as 5% gel aromatics) can be improved by severe hydrorefining so as to minimize or eliminate the presence of aromatics hydrocarbons in said oils.

The usual hydrotreating has little or no effect on the traction properties of a naphthenic oil, however, if the hydrogenation is so severe as to virtually eliminate the presence of aromatic hydrocarbons in the resulting hydrogenated oil, the traction properties will be significantly improved (perhaps due to the type of naphthene to which the aromatics are converted). This discovery is illustrated in Tables I, II, and III of U.S. 3,595,796.

Residual aromatics (e.g., less than 1%) can be removed by contacting the severely hydrogenated distillate with silica gel. The resulting completely hydrogenated naphthenic distillate contains more than twice the weight of naphthenes (a total of about 70 naphthenic carbon atoms) than is found in the usual hydrorefined naphthenic oil.

stock, useful as a lubricant when contained in a traction In our severely hydrorefined naphthenic oils, at least 15% (preferably over 25%) by weight of the naphthenes contained therein will result from perhydrogenation of the aromatics contained in the oil prior to hydrogenation.

In another embodiment a saturated naphthenic traction fluid is prepared by severe hydrogenation (to less than 1% gel aromatics) of a naphthenic distillate (or an acid refined or solvent refined naphthenic oil) or a hydrorefined naphthenic distillate, containing at least 10% gel aromatic hydrocarbons and having a kinetic viscosty at 210 F. less than 3.0, and preferably less than 2.5 cs. Such fluids are especially useful, due to their low initial viscosity, as traction fluids in external submarine drives. For example, such an oil is obtained by severe hydrorefining of a 50 SUS (at F.) naphthenic distillate containing 40% aromatics, and having a 260 UVA of 5.4.

Such a severely hydrogenated light naphthenic distillate can also be blended with perhydrogenated oligmer oils (such as the perphoydrogenated hydrindan-trimer of u-methyl styrene), as is illustrated by Oil 51 in Table 11 of U.S. 3,595,796. Our severely hydrogenated naphthenic oils can be distinguished from the naphthenic oils of Rounds in J. C&E Data, Ibid., in that our oils contain more than 50%, and preferably more than 75% of naphthenic hydrocarbons (by the method of vanNes and vanWesten) and contain less than 2% of aromatic hydrocarbons.

Other embodiments of the invention involve the discovery that fluid G -C naphthenes containing a perhydroterphenyl, or fluid C C naphthenes containing perhydrofluorene as a structural nucleus, are useful as lubricants for traction drive transmissions, Whether the drive is of a fixed or variable ratio.

The perhydrogenated terphenyl and fluorene compounds which are useful in the present invention can be obtained by conventional synthesis as by the hydrogenation of terphenyls, fluorene or substituted fluorenes orterphenyls, or partially hydrogenated derivatives thereof,

15 as with Raney nickel catalyst at 200 C. and 3000 p.s.i. of hydrogen. The substituted fluorene derivative can be in relatively pure form, or can be present in concentrations as low as 10% in distillate fractions from petroleum refining or petrochemical manufacture.

One embodiment is an espectially useful power transmission system comprising a fixed ratio, roller traction drive of the type described in the aforementioned AIAA paper of Hewko, or a variable ratio drive of the type shown in the attached drawings labelled FIGS. 1 and 2, and as a lubricant therefor, a composition comprising a hydrocarbon base stock boiling in the lubricating oil range, having a viscosity at 210 F. in the range of 2.0- 12.0 cs., and having an ultraviolet absorbance at 260 mM (260 UVA) below 0.5 (perefarbly below 0.1), said base stock containing at least 5%, preferably at least 10 percent, by weight of a C -C perhaydroterphenyl or a C -C perhydrofluorene. For example, a transmission comprising the fixed ratio roller traction drive of the Hewko AIAA paper, and as a lubricant, a hydrocarbon base stock containing 10 volume percent of perhydrofluorene and 90 volume percent of a 5 cs. (at 210 F.) polyisobutylene oil wherein over 33 percent of the repeating units are of the gem-dimethyl configuration, permits the resulting power transmission system to operare at a higher torque throughput than with the better of the naphthenic mineral oils shown in FIG. 3, at page 4, of the Hewko paper.

A preferred embodiment of our invention is a power transmission system comprising a friction drive transmission, and as a lubricant therefor, a composition comprising a hydrocarbon base stock boiling mainly above 500 F. and having a kinematic viscosity at 210 F. in the range of 1.5200.0 (preferably 1.8-20) cs., said base stock comprising perhydrogenated orthoterphenyl or perhydrofluorene or a saturated, O -C hydrocarbon substituted derivative of terphenyl or a hydrocarbon substituted derivative of perhydrogenated fluorene wherein said hydrocarbon substituent is selected from the group consisting of alkyl, cycloalkyl, and alkylcycloalkyl.

Perhydrofluorene (having an ASTM-VI of 105, a KV of 2.5 cs. and a pour point less than C.) and C C alkyl substituted derivatives thereof (e.g., the dimethyl derivatives) are also useful as components of traction fluids, as are perhydroacenaphthalenes. Preferred perhydrogenated acenaphthalene and fluorene derivatives can be obtained by perhydrogenation of the following fiuorene compounds (or hydroderivatives thereof): I-(S-acenaphthyD-butane 1-(5 -acenaphthyl) -hexane 9-methylfluorene 9-(4-methyl-benzylidene)-fluorene 9-phenyl-fluorene 1, 8-dimethyl-9 2-tolyl) -fluorene 9-benzylidene-fluorene Preferred perhydrogenated terphenyl derivatives can be obtained by perhydrogenation of orthoterphenyl (or hydro-o-terphenyls) or C C methyl substituted-o-terphenyls or by hydrogenation of hydrocarbon streams containing at least of o-terphenyl.

To control fluid loss, it is preferred that the base stock boil no lower than in the gas oil range, more preferably the base stock should boil in the lube oil range. Where the base stock boils mainly below the gas oil range, the fabrication of a transmission utilizing such a stock as a lubricant becomes costly because tolerances become critical and the seals must be very tight in order that there is no undue loss of the fluid through vaporization. Such highly volatile fluids, however, can be quite useful as lubricants when the transmission is properly designed so as to prevent fluid loss by vaporization and when the pressure-volume-temperature relationship within the transmission is such that a substantial portion of the fluid remains in liquid phase during the operation of the transmission.

Broadly, the oil should boil mainly above 500 F. and, preferably, mainly above 600 F. and (except in greases) have a point below 950 F. Distillation of such stock is preferably conducted at reduced pressure, including vacuum-steam distillation, (as under 5 mm. Hg.) to avoid thermal decomposition.

Normally, our monomer-free perhydrogenated terphenyl and fluorene compounds will be produced from distillate fractions obtainable in a petroleum refinery, such as the recycle from catalytic cracking or the recycle from thermal demethylation of alkyl aromatic hydrocarbons. Satisfactory traction fluids can be compounded from such perhydrogenated distillate fractions, when the distillate fraction contains at least 5% (preferably at least 15%) of terphenyl, fluorene, hydrofluorene, or hydroterphenyl compounds.

When the hydrocarbon base stock of our invention consists essentially of naphthenes corresponding to perhydrogenated terphenyl or fluorene or alkyl and cycloalkyl derivatives thereof, the base stock has a low viscosity index, and therefore, has poor low temperature properties, such as the pour point. We have discovered that novel traction fluids having a traction coeflicient at least 10% greater than that of DMAP (at 600 ft./min., 200 R, 400,000 psi.) and having an ASTM-VI greater than 40, can be prepared by blending from 1-20 parts by weight of fluid, branched paraffin hydrocarbons containing an average of over 3 branches per chain, with fluid C C naphthenes containing perhydroterphenyl or perhydrofluorene as a structural nucleus.

We have discovered, surprisingly, that a particularly useful power transmission system comprises a friction drive transmission and, as a lubricant therefor, a substantially saturated hydrocarbon base stock having a 260 UVA below 0.5 and comprising at least one member selected from the class consisting of perhydro-ortho terphenyl, (E -C hydrocarbon substituted derivatives of terphenyls, perhydrofiuorene and the (D -C hydrocarbon substituted derivatives of perhydrofluorene, the perhydroterphenyl or perhydrofluorene compound being present in an amount of at least 5% by Weight of the base stock, and wherein there is present from 0.1-20 parts by weight, based on said perhydrofluorene, of a fully hydrogenated, liquid C C C C C or C olefin polymer, copolymer, or terpolymer. Preferably said olefin comprises isobutylene, 3-methylbutene1, 4-methylpentene-1, or 2,3-dimethy1butene-1. More preferably at least 35% (most preferably 90100%) of the repeating units (exclusive of terminal methyl groups) of said olefin polymer have the structure wherein R"; is hydrogen or methyl, and when R"; is hydrogen, R" is isopropyl or isobutyl, and when R" is methyl, R is methyl, ethyl, isopropyl, or isobutyl.

Ser. No. 679,851, (now US. 3,598,740 issued Aug. 10, 1971 discloses a power transmission system comprising a traction drive transmisison and, as a lubricant therefor, a hydrocarbon base stock having a kinematic viscosity at 210 F. in the range of 15-2000 cs., said base stock comprising a paraffinic oil containing less than 1% by weight of aromatics having an ultraviolet absorptivity at 260 millimicrons of less than 0.5. Preferably, the paraflinic oil is obtained by severe hydrogenation of a petroleum oil having a percent C greater than 60, a percent C greater than 30, and a percent C greater than 2. The paraffinic oil, preferably, has an ASTM-VI greater than 80, a refractive index at 68 F. greater than 1.47 and an SUS viscosity at F. in the range of 60-3000.

In another embodiment, the base stock contains from 575% of a Gu -C40 naphthene having a glass transition temperature in the range of -90 to 30 C. and containing, as a structural nucleus, a cyclohexyl hydrindan, di(cyclohexyl)-a1kane, spirodecaue, spiropentane, perhydrofluorene, perhydrobiphenyl, perhydroterphenyl, decalin, norbornane, perhydroindacene, perhydrohomotetraphthene, perhydroacenaphthene, perhydrophenanthrene, perhydrocrysene, perhydroindane 1 spirocyclohexane, perhydrocarylophyllene, pinane, camphane, perhydrophenylnaphthalene, perhydropyrene, or adamantane. Although the conventional paraflinic and naphthenic petroleum cils contain minor amounts of individual members of some or all of the above types of naphthene, it is very rare to encounter more than 5% of any individual class in a given petroleum lubricating oil. Therefore, a given paraffinic oil, of the type useful in our invention, should be analyzed to determine its content of some or all of the aforementioned classes of naphthene and, at least one member of at least one of the above classes of naphthene should be added to the paraflin oil in sufiicient quantity to increase the traction coefficient thereof. Preferably the traction coefiiicent at 600 ft./min. 400,000 p.s.i., 200 F., should be increased at least by means of such addition of naphthenes.

Another useful component of a blended traction fluid is a C -C adamantane compound containing no elements other than carbon, hydrogen, fluorine and oxygen and wherein if oxygen is present, said oxygen is in a hydroxyl, ketone, or carboxylic acid radical or is combined in an ether or an ester linkage. Such compounds are generally known to the art or are described in the previously cited applications Ser. Nos. 679,801; 876,993; 003,- 256; 056,680; 080,779; 091,183 and the applications of Driscoll and Haseltine, Jr., filed May 17, 1971 and June 11, 1971. A preferred base stock comprises such an adamantane compound and a partially or fully hydrogenated polyolefin oil (especially a polyvinylidene, such as polyisobutylene, having a high degree of gem substitution as in the previously cited applications Ser. Nos. 028,942; 052,300; 052,301; 052,771, 052,772; 052,773; 052,268 and the applications Driscoll and Haseltine, Jr.).

In general, the traction coeflicient of any hydrocarbon oil, whether synthetic or a refined mineral oil, can be improved by addition thereto of an effective amount (typically 0.5-25 weight percent) of such an adamantane compound or of a polar compound of the type disclosed in the application of Driscoll and Haseltine, Jr., filed June 11, 1971.

Another preferred embodiment is a hydrocarbon base stock, useful as a traction fluid, comprising a mixture of substituted adamantanes derived by contacting a petroleum hydrocarbon stream which is substantially free from aromatic or olefinic unsaturation and which contains at least one perhydroaromatic hydrocarbon having three rings and at least 12 carbon atoms at a temperature in the range of -5 to +50 C. with an aluminum halide catalyst, and continuing such contact until at least a substantial proportion of the perhydroaromatic has been converted to hydrocarbon product having admantane structure. The adamantanes so produced can be further converted by alkylation, as by the method of the aforementioned Schneider patent application.

One such blended traction fluid comprises perhydrophenanthrene, and from 01-10 parts, based on the perhydrophenanthrene, of cyclopentyldimethyladamantane, and can also contain one or a mixture of members selected from a synthetic liquid paraflinic lube, any of which can be unhydrogenated, partially hydrogenated, or fully hydrogenated (including hydrocracked oils).

Due to the high cost of the adamantane compounds, it is only in highly specialized applications where economics will permit their use, per se, as traction fluids. However, due to their high coefficient of traction, compared with their viscosity index, the adamantanes are especially useful components for blending with other naphthenes, with branched paraflins, and with hydrogenated naphthenic or paraffinic petroleum oils in the compounding or traction fluids. Another adamantane compound which is useful as a traction fluid or as a component of a blended traction 18 fluid, is obtained by perhydrogenation of benzyladamantal ether, which can be obtained by the method in J. Org. Chem., Vol. 27, page 1933 (June 1964).

US. 3,595,796 contains many examples of naphthenes and branched paraflins useful in the present invention and examples of their use as components of blended traction fluids.

, ILLUSTRATIVE EXAMPLE A comparison of the maximum torque which can be obtained without slippage with four fluids in a traction transmission is shown in Table V below, along with the viscosity index and the coeflicient of traction obtained in the laboratory test device at 500,000 p.s.i., 200 F., and 1000 ft./min. It can be seen that Oil 1, a naphthene-paraffin blend, possesses the best combination of traction properties and fluidity properties (e.g., the viscosity index). Oil 1 has only 9% greater coefficient of traction in the laboratory device than Oil 23, poly-mixed butenes and yet is able to withstand 32% greater torque without slippage than can Oil 23. Note also that Oil 5, containing about 20% of perhydrogenated a-methyl styrene trimers, has the best traction properties but has the lowest viscosity index of the four oils.

In general, naphthene-paraflin blends (such as oil #1 in Table IV) can be compounded from polymeric reaction products of at least one of the olefinic hydrocarbon monomers taken from the group consisting of ethylene, propene, butene, pentene, hexene, heptene and octene, including copolymers of two or more of such monomers, said polymeric reaction product being substantially free from olefinic unsaturation. The usual oils prepared from polyolefins and copolymers of polyolefins have considerable olefinic unsaturation, for example, one commercially available polybutene has an iodine number of 48. Preferably, oils prepared from such highly unsaturated polyolefins are hydrogenated to produce a hydrogenated poly olefin oil which is substantially free from olefinic unsaturation. Preferably, the oils have an iodine number less than 5, more preferably, less than 2. More preferred than the iodine number as a means of defining residual olefinic unsaturation in polymers which are substantially free from olefinic unsaturation is the ultraviolet absorption in the region of -195 millimicrons (herein sometimes referred to as UCA). Preferred fluids are a hydrogenated polypropylene having a 195 UVA no greater than 2.0 (e.g., 1.88), even more preferred is a hydrogenated polybutene having a 195 UVA less than 1.0 (e.g., 0.77). Less preferred, but operable blended fluids can be prepared by blending one or more naphthene hydrocarbons with the polymeric reaction product of at least one of the olefinic monomers taken from the group consisting of propene, butene, and pentane, said polymer having a molecular weight of 300 to 500. Fluids comprised of such polymeric reaction products are useful in the combination of a friction drive machine comprising a power input member and a power output member in tractive rolling contact relationship, an oxidation-resistant fluid film between said members and said fluid. Similarly, such fluids comprised of such polymeric reaction products are useful in the combination of a toric transmission mechanism comprised of at least 2 axially aligned opposing power transmitting race members, each having a toric raceway in its opposing face and at least one roller member disposed between said race members in tractive rolling con tact relationship with each of said raceways, a fluid film between said racers ad roller at the points of contact and said fluid. Examples are such a'friction drive or such a toric transmission mechanism wherein said fluid is comprised of polybutene having a molecular weight of about 400, and preferably, wherein said polybutene is a hydro, genated polybutene.

Useful blended traction fluids similar to the naphtheneparaffin blend of Table IV can be prepared by blending at least 5 volume percent (more preferably, at least 15 volume percent) of the polymeric reaction product of at least one of the olefinic hydrocarbon monomers taken from the group consisting of ethylene, propene, butene, pentene, hexene, heptene and octene (most preferably, said polymeric reaction product having been hydrogenated so as to be substantially free from olefinic unsaturation) and as the naphthene component of a (E -C organic nitude than the traction coeflicients reported in the aforementioned U.S. Pats. 3,411,369 and 3,440,894 of William C. Hammann and Robert C. Schisla. In order to provide common basis for comparing the present data with that of said patents, the following traction coefiicients are presented, as measured by the Rounds method:

Hammond et a1. Method 01 Rounds 400, 000 500,000 psi. 400,000 p.s.i. p.s.i.

Ft Imin r 750 600 750 1,000 1, 000

Perhydro-.o-terphenyl (Oil B)- 073 065 O63 062 050 Cosden polybutene (01123)" 060 050 047 045 044 ASTM Oil 3 (Oil 35) 042 039 037 042 Bis (2, 4, 6 trimet-hyl cyclohexyl) methane 061 045 042 040 042 Perhydro-styrene dimerizate (Oil 15)-.. 049 049 049 052 TIPD (Oil 17). 052 O50 048 044 Perhydro-polybutene (Oil 19) 053 050 047 042 Perhydro-alphzmnethyl styrene Norm-All measurements at 200 F.

liquid having at least one saturated ring having a coetficient of traction of at least 0.06 as defined in French Pat. No. 1,541,833. The naphthene component can be a fused, saturated compound having from 2 to 0 fused rings and a total carbon atom content of from about 9 to about 60 as described in US. Pat. 3,411,369. As the paraffinic or non-naphthene component of a useful blended traction fluid is a hydrocarbon having an acyclic structure with at least three quarternary carbon atoms, as described in French Pat. No. 1,541,833. In general, blended traction fluids can be prepared wherein at least one component is selected from the group consisting of parafiins, hydrogenated paraflinic lube oil containing less than 1% gel aromatics, hydrogenated naphthenic lube oil containing less than 1% aromatics, and paraffin oils, (e.g., polymeric reaction product of at least one C -C olefinic hydrocarbon monomer, wherein the polymeric reaction product is subtantially free from olefinic unsaturation) and as a second component at least one member selected from the group consisting of C -C organic liquids having a coeflicient of traction of at least 0.06, at least one saturated ring and wherein up to eight carbon atoms may be replaced with oxygen or phosphorous atoms, and fused, saturated compounds having from 2 to 9 fused rings and a total carbon atom content of from about 9 to about 60, up to eight of which atoms can be replaced by atoms selected from the group consisting of oxygen, nitrogen, phosphorous and silicone (e.g., see US. 3,411,369 and French Pat. 1,541,833). One useful liquid, having at least one saturated ring is 1,3-(5,7-dimethyl)adamantyl dipelargonate (DMAP).

In general, the choice of molecular weight of components of traction fluids is determined primarily by the desired viscosity characteristics of the fluid (taking into consideration the effect of any other components, such as low VI naphthenes or highly viscous VI improvers). The following are examples of the relationship between the average molecular weight of polyolefin oils and the viscosity at 210 F.

Average mol. KV 210 F. weight Oil number from tables I and II:

Due to day-to-day test variations, all measurements are normalized, by comparison with a standard (here Oil 23) as by means of the following equation for 600 ft./ min., 400,000 p.s.i. and 200 F.

Oil 23 measured coefiioient 0.045

Sample measurement coefiicient Normalized coefiicient the bis (2,4,6 trimethyl cyclohexyl) methane has a KV of 2.94 cs. and KV of 19.61,

20 (ITO-8886,

and a VTF-VI of 104. In making traction coefiicient measurements by the Rounds method, the measurement is frequently made, at a number of different velocities (from 0 to 750 ft./min.) and a curve is drawn from which data at other velocities can be taken (by extrapolation). The properties of ASTM Oil No. 3 (which is sold under the trade name Circolite) are reported in greater detail in Tables I and II of US. 3,595,796 (see Oil 35).

In the present invention the preferred acyclic tractants are substantially saturated (e.g., they have a bromine number less than 5, more preferably less than 1). However, the acyclic synthetic liquid C C olefinic homopolymers, copolymers or terpolyrners described herein can also be useful per se as tractants or as components of tractant blends.

The oxidation stability of these olefinic acyclic polymers is improved by hydrogenation, either partially (as to a bromine number in the range of 5-30) or by substantially complete saturation (e.g., perhydrogenation to produce a synthetic acyclic paraflin).

Table II of US. 3,595,796 reports the Tag acid number (TAN) and percent increase in kinematic viscosity at 100 F. (KV of the used oil, that is, the oil after testing for traction coefiicient. Similarly, after extended use in a transmission, the increase in acid number and viscosity (caused by oxidation) can be such that the traction fluid, consisting of the base oil and lubricant additives, must be replaced. Such a used or oxidized fluid can be reclaimed or revitalized by contacting with an adsorbent, as by passing the oil through a column containing silica gel and activated charcoal (which can be admixed or in separate layers). Other adsorbents (e.g., fullers earth or acid-activated clay, alumina, spent alumino-silicate catalyst, etc.) or adsorbent admixtures can be used. Treatment with a Lewis acid (e.g., HF, H preferably followed by washing, can be used instead of, or in combination with the adsorbent contacting. Such treatment will reduce or remove polar lubricant additives; therefore, the reclaimed oil can be replenished with such additives prior to reuse.

NH mm mmo IIIII I II owl E. wm IIIIIIIIII aw wm o o R a II.I.IIIIIIIIIIIIIIIIIIIIIIIII.

QiQIWQQMQDHQW Ow IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIHIHO nH ow R. ww

gm$m mwwmmn mmbb I I I II I ma ma I I I II IIIIIIIIIIIIIIIIIIII 3 QB mmdfi A IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII I n mm 2 2 IIIII 3 all ow an man can Sm coma. mw M am am um ow wm w IIIIIIIIIIIIIIIIIIIIIIII 030 one wmwc 96 e3 IIIIIIIIII mm 8 mm mm 3 ow an wwo m I N30 I 83 ammo IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII c3 o I s E 32 am no an em mmwc mwwo

mwc n $032 22 538w 82 cm IIIIIIIIIIIIII oToNImmmm mim on IIIIIIII oTcNbmmm mHnH cm IIIIIIIIIIIIIIIIIII.IIIIIMMIP%MOAH I IIII oSmmnBTEmmmnMom}: I I I I I I sommfia ohnmmm owBm cEmmnBTEmmmn 28m oHwNmmBTcEmmn be? IIIIIIIIIIIIIIIIIIIIIII I ciommmm obnmmm .omn cSNmmBH oBmmn .oiow oSmmmETEnmmm omBb IIIIIIIIIIIIIIIIIIIIIII I oEmmQcTohmmmn 61cm IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIImEQ IIIIIIIcm m: mbH flbH QZ QS wmH IIIIIIIIIIIIIIIII N mNn$n Jam 05 Thmwmmw H HO nH on IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIQHnH on g E m3 2 mm o 3 Q Sn gmmmQm o mmm minw M moz QMWIIEINS mmH IIIIIIImm mS hmH onfi II mH IIIIIIImm mmH IIIIIIUEH IIII nna IIIIIII: III mwH EH cnn II IIIIIQ wm ofi The invention claimed is:

1. A hydrocarbon base stock, useful as a lubricant having a kinematic viscosity at 210 F. in the range of 1.5- 200.0 es and comprising a blend of (i) at least one part by weight of a synthetic oil containing at least 95% of C -C naphthene and (ii) from 01-20 parts by weight, based on said naphthene of at least one member from at least one of the following groups (a), (b) and (c):

(a) a synthetic liquid C -C olefin homopolymer, co-

polymer, or terpolymer;

(b) a member from group (a) above which is at least partially hydrogenated; and,

(c) a severely hydrorefined naphthenic mineral oil lube or paraffim'c mineral oil lube containing less than 1% of gel aromatic hydrocarbons,

and wherein said base stock containing said blend has a coefiicient of traction, measured at 600 ft./min., 200 R, 400,000 psi, at least as high as that of ASTM Oil N0. 3.

2. A hydrocarbon base stock according to Claim 1 and wherein said C -C naphthene has a glass transition temperature in the range of -90 to 30 C. and contains, as a structural nucleus, a cyclohexyl hydrindan, di(cyclohexyl) alkane, spirodecane, spiropentane, perhydrofluorene, perhydrobiphenyl, perhydroterphenyl, Decalin, norbornane, perhydroindacene, perhydrohomotetraphthene, perhydroacenaphthene, perhydrophenanthrene, perhydrocrysene, perhydroindane-l-spirocyclohexane, perhydrocarylophyllene, pinane, camphane, perhydrophenylnaphthalene or perhydropyrene.

3. In a power transmission system comprising a traction drive transmission and a lubricant therefor, the improvement wherein said lubricant contains the hydrocarbon base stock according to Claim 1.

4. The transmission system of Claim 3 wherein said lubricant contains the hydrocarbon base stock of Claim 2.

5. In a method for improving the coeflicient of traction between relatively rotatable members in torque transmitting relationship, the improvement which comprises introducing to the tractive surfaces of said members a lubricant containing the base stock of Claim 1.

6. A method of Claim wherein the lubricant contains the base stock of Claim 2.

7. A lubricant composition containing from 95-50% of the base stock of Claim 1- 8. The hydrocarbon base stock of Claim 1 wherein said blend contains said naphthene and at least one member from said group (a) or (b).

9. The hydrocarbon base stock of Claim 2 wherein said blend contains said naphthene and at least one member from said group (a) or (b).

10. Process for increasing the traction coefiicient of a hydrorefined petroleum mineral oil or liquid polyolefin oil or hydrogenated liquid polyolefin oil lubricant composition having a kinematic viscosity in the range of 1.5-200 cs. at 210 F., said process comprising incorporating in said composition an amount of a synthetic oil containing at least 95 of a C -C naphthene, said amount being suflicient to increase the traction coeflicient by at least 10% as measured at 600 f-t./min., 200 F. and 400,000 p.s.1.

11. The process of Claim 11 wherein said oil contains at least 50 Weight percent of naphthenes containing as a mutual structural nucleus one member selected from a cyclohexyl hydrindan, di(cyclohexyl) alkane, spirodecane, spiropentane, perhydrofluorene, perhydrobiphenyl, perhydroterphenyl, 'Decalin, norbornane, perhydroindacene, perhydrohomotetraphthene, perhydroacenaphthene, perhydrophenanthrene, perhydrocrysene, perhydroindane 1- spirocyclohexane, perhydrocarylophyllene, pinane, camphane, perhydrophenylnaphthalene or perhydropyrene.

12. Process of Claim 12 wherein said lubricant has an ASTM VI of at least 40.

References Cited UNITED STATES PATENTS 3,493,505 2/1970 Ries et al. 252-73 3,450,636 6/1969 Rausch 252- 3,394,603 7/1968 Rounds 74-200 3,440,894 10/ 1966 I-Iamman et al. 74-200 3,608,385 9/1971 Duling et al. 252-73 3,597,358 8/1971 Duling et al 252-73 3,595,796 8/1971 Duling et al. 252-73 FOREIGN PATENTS 1,806,401 6/ 1969 West Germany 0-102 OTHER REFERENCES Rounds, Journal of Chemical & Engineering Data, Vol. 5, No. 4, October 1960, pp. 499-507.

HERBERT LEVINE, Primary Examiner U.S. Cl. X.R. 208-19; 252-73 

1. A HYDROCARBON BASE STOCK, USEFUL AS A LUBRICANT HAVING A KINEMATIC VISCOSITY AT 210*F. IN THE RANGE OF 1.5200.0 C.S. AND COMPRISING A BLEND OF (I) AT LEAST ONE PART BY WEIGHT OF A SYNTHETIC OIL CONTAINING AT LEAST 95% OF C13-C40 NAPHTNENE AND (II) FROM 0.1-20 PARTS BY WEIGHT, BASED ON SAID NAPHTNENE OF AT LEAST ONE MEMBER FROM AT LEAST ONE OF THE FOLLOWING GROUPS (A), (B) AND (C): (A) A SYNTHETIC LIQUID C3-C8 OLEFIN HOMOPOLYMER, COPOLYMER, OR TERPOLYMER; (B) A MEMBER FROM GROUP (A) ABOVE WHICH IS AT LEAST PARTIALLY HYDROGENATED; AND, (C) A SEVERLY HYDROREFINED NAPHTNENIC MINERAL OIL LUBE OR PARAFFINIC MINERAL OIL LUBE CONTAINING LESS THAN 1% OF GEL AROMATIC HYDROCARBONS, AND WHEREIN SAID BASE STOCK CONTAINING SAID BLEND HAS A COEFFICIENT OF TRACTION, MEASURED AT 600 FT./MIN., 200*F., 400,000 P.S.I., AT LEAST AS HIGH AS THAT OF ASTM OIL NO.
 3. 